POWER MODULE FOR SUPPLYING ELECTRICAL LOAD OF AN AIRCRAFT, POWER SUPPLY SYSTEM AND ASSOCIATED METHOD

Description

Domaine technique

[0001] The present invention relates to the field of protection against electric arcs in a power supply system for at least one electrical load of an aircraft.

[0002] Climate change is a well-known major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain less energy-intensive and more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences, with the aim of improving aircraft energy efficiency.

[0004] This sustained research and development work focuses in particular on new generations of hybrid thermal and electric aircraft engines. The Applicant's objective is, among other things, to develop aircraft incorporating a high-power electrical generation system. This would increase the proportion of electrical equipment on board in order to reduce fuel consumption.

[0005] In practice, with reference to the [ Fig.1 A simplified power supply system according to the prior art is shown for supplying an electrical load L from a power source S via a power device DP. In practice, the power source S can be an electric battery, a fuel cell, or an electric machine capable of operating as both a motor and a generator to extract mechanical energy from a shaft of an aircraft turbomachine to produce electrical energy. In practice, a power supply system comprises a plurality of power sources S and a plurality of electrical loads L.

[0006] In a well-known way, with reference to the [ Fig.1 A DP power device comprises one or more power modules M1 to perform electrical energy conversion, for example, from inverters. A power module M1 contains several electronic components controlled to perform the conversion function. Their number depends on the amount of energy the power module M1 must convert. In practice, the DP power device is configured to receive a PCONS control command, such as switch switching commands, which is transmitted to each power module M1 to configure the electrical energy conversion according to the requirements.

[0007] With reference to the [ Fig.2 A power module M1 conventionally comprises a substrate 11 on which power electronic components 12, in particular electronic chips, are mounted. In this example, the power electronic components 12, whether controlled or not, are connected by electrical connections 14 to enable electrical connection. The power electronic components 12 are protected by an encapsulation layer 15, which provides electrical insulation, and a protective cover 17. The power module M1 includes at least one power connector 13P configured to interface with a power source S or an electrical load L. The power module M1 also includes at least one data connector 13D, to enable the control of the controllable power electronic components 12.A controllable component is defined as a component whose state can be modified by an electrical signal sent to it. Power transistors are examples of controllable components. The nature of the signals carried by the 13D data connector can vary depending on the nature of the electrical commands and information exchanged with the PCONS control setpoint. The structure of such a power module M1 is known to those skilled in the art.

[0008] In practice, various faults can occur at any point in the power system: a short circuit in equipment or wiring, damage to a component subjected to unexpected stress, a malfunctioning component, an electrical arc, etc. To protect the various pieces of equipment against excessively high currents, it is common practice to use controllable protective devices (OPCs) to isolate and protect a portion of the equipment. OPCs are generally electromechanical contactors or so-called static components, employing semiconductor components. An OPC allows the fault to be isolated, for example, from a power source S as illustrated in [ Fig.1 As is known, in the event of a fault being detected in a power source S, the controllable protection devices OPC are controlled in such a way as to reconfigure the power supply system to supply the electrical loads L with the power sources S that are available.

[0009] To provide redundancy for an OPC controllable protection device, it is often necessary to provide another protection component with a dissimilar breaking technology, for example, a fuse technology.

[0010] With reference to the [ Fig.1 An OPF fuse-type protective device allows for the permanent interruption of an electrical connection. As is known, such an OPF fuse-type protective device, for example made of silica, changes state to absorb an electric arc and interrupt the current flow on the power line to which it is mounted. Under the effect of a high current, the silica vitrifies, thus breaking the current flow. Advantageously, an OPF fuse-type protective device can absorb a large amount of electrical energy to ensure the extinction of the electric arc without causing material projection or other damage.

[0011] In practice, due to its positioning in series with the equipment to be protected, for example a power source S as illustrated in the [ Fig.1 The OPF fuse-type protection device must be sized to withstand the main current and transients on the supply line connecting the power source S to the power device DP. In the event of a short circuit and a fault in the OPC controllable protection device, the OPF fuse-type protection device will interrupt the current at a high breaking value. In practice, as the current increases to the breaking current, the currents flowing through the power module M1 also increase and are likely to damage the power electronic components 12 of the power modules M1. In other words, when the OPF fuse-type protection devices interrupt the current flow, the power electronic components 12 of the power modules M1 are likely already damaged, which is a significant drawback. Restoring the system to service is therefore costly.Furthermore, OPF fuse-type protection devices are bulky, have high heat dissipation, and are cooled by natural air convection. To reduce the risk of overheating, an OPF fuse-type protection device is generally oversized. This significantly impacts the power supply system, which must remain compact.

[0012] An immediate solution to eliminate this drawback would be to provide OPF fuse protection devices with a lower breaking current value, but this would lead to an untimely interruption in the event of a fluctuation in the current on the supply line between the power source S and the power device DP.

[0013] The invention thus aims to eliminate at least some of these drawbacks by proposing a fusible protection device that can protect the electronic power components of a power module that would be faulty, without increasing complexity and size.

[0014] We know from application US20070085181A1 a power module comprising semiconductors and a protection device to prevent destruction by explosion of the power module following the flow of excessively high currents. PRESENTATION DE L'INVENTION

[0015] The invention relates to a power module for supplying at least one electrical load of an aircraft, according to claim 1.

[0016] The invention is remarkable in that the power module includes at least one fusible protection layer in which extends at least a portion of the power electrical connection, the fusible protection layer being configured to change state when a current, exceeding an permissible threshold, flows in the portion of the power electrical connection so as to definitively stop the flow of current in said portion.

[0017] Thanks to this invention, a fuse protection device is integrated directly into the power module. This allows for the permanent interruption of current flow in a portion of a power electrical connection. Furthermore, this fuse protection device keeps the power electronic components within an encapsulation layer for their protection. The fuse protection layer absorbs the energy released by an electrical arc and stops its flow. Thus, an electrical arc is contained locally, protecting the power electronic components. Having fuse protection integrated into the power module is a significant advantage because it eliminates the need for a dedicated fuse-type protection device, which is bulky and complex to install.

[0018] According to one design, several electrical connections include a portion within the fusible protective layer. This allows for the permanent interruption of current flow in those portions of the electrical connections. According to a preferred design, all electrical connections include a portion within the fusible protective layer.

[0019] Preferably, the fusible protection layer covers several components of the power module, especially the semiconductors (the chips), potentially all electrical connections, passive components, or any other component placed in the power module that may release energy during a fault.

[0020] In one aspect, the electrical power connection is linked between two electronic power components.

[0021] According to one aspect, the power electrical connection is linked between at least one power electronic component and at least one power electrical connector comprising at least one portion extending outside the encapsulation layer.

[0022] In one aspect, the electrical power connection is partly in the encapsulation layer and partly in the fuse protection layer.

[0023] In one aspect, the power module includes at least one remote connector linking the power electronics component to the power electrical connection, with the power electrical connection extending only within the fusible protection layer. The fusible protection layer absorbs all the heat associated with the fault. The power electronics components remain protected within the encapsulation layer.

[0024] Preferably, the offset connector is positioned on the support substrate.

[0025] Preferably, the power module includes at least one printed circuit board mounted at the interface between the encapsulation layer and the fuse protection layer, with the remote connector linked to the power electrical connection via the printed circuit board. The printed circuit board includes the power electrical connections and can be conveniently replaced.

[0026] In one aspect, the power module includes at least one electrical data connection linked to a data connector, the electrical data connection having at least a portion extending into the fuse protection layer. Advantageously, the power electronic components are fully protected.

[0027] The invention also relates to a power supply system for at least one aircraft electrical load comprising at least one power device comprising at least one power module as previously described.

[0028] The invention also relates to a method of manufacturing a power module for supplying at least one electrical load of an aircraft, according to claim 9.

[0029] The fusible protective layer is deposited on the encapsulation layer.

[0030] In one aspect, the fusible protective layer is deposited directly onto the encapsulation layer, which facilitates assembly.

[0031] In one design, the fusible protective layer is deposited indirectly onto the encapsulation layer, for example, using an intermediate support. This intermediate support serves as an interface for the fusible protective layer. This allows the use of materials for the fusible protective layer that would be incompatible with the encapsulation layer. In one design, the intermediate support is a printed circuit board, and electrical connections are specifically made on the printed circuit board to perform the fusible function. PRESENTATION DES FIGURES

[0032] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects. There [ Fig.1 ] is a schematic representation of a prior art power system. The [ Fig.2 ] is a schematic representation of a power module according to the prior art. The [ Fig.3 ] is a schematic representation of a power supply system according to the invention. The [ Fig.4 ] is a simplified schematic representation of a power supply system according to the invention. The [ Fig.5 ] is a schematic representation of a power module according to an embodiment of the invention. The [ Fig.6 ] is a close schematic representation of an electrical connection of the [ Fig.5 ] including a portion mounted in the fusible protective layer. The [ Fig.7 ] is a close schematic representation of the electrical connection of the [ Fig.5 ] after absorption of an electric arc by the fusible protective layer. The [ Fig.8 ] is a schematic representation of a power module according to another embodiment of the invention.

[0033] It should be noted that the figures explain the invention in detail for implementing the invention, said figures being of course able to serve to better define the invention where appropriate. DESCRIPTION DETAILLEE DE L'INVENTION

[0034] With reference to the [ Fig.3 [Figure ] shows a power supply system for supplying a plurality of electrical loads L from a plurality of power sources S. A power source S can be, in particular, an electric battery, a fuel cell, or an electric machine configured to operate as a motor or generator to extract mechanical energy from a shaft of an aircraft turbomachine. The electrical load L can be, in particular, an actuator or a motor, specifically one comprising two stator stars to improve redundancy.

[0035] Still referring to the [ Fig.3 The power supply system includes a plurality of DP power devices to convert and process electrical energy from power sources S to power electrical loads L. As an example, a DP power device may include several power modules to power the different stator stars of an electrical machine.

[0036] Still referring to the [ Fig.3 ], the power supply system includes a plurality of controllable OPC protection devices, for example contactors, so as to allow isolation of a fault in equipment and to allow reconfiguration of the power supply system for degraded operation.

[0037] In simplified terms, with reference to the [ Fig.4 ], for the sake of clarity and conciseness, it is represented as a system supplying a single electrical load L from a single power source S. A [ Fig.4 The power supply system includes a DP power device to convert and process the electrical energy from the power source S to supply the electrical load L. A controllable OPC protection device is provided on the supply line connecting the power source S to the DP power device.

[0038] As illustrated in the [ Fig.4 ], the DP power device comprises a plurality of power modules M. Preferably, each power module M is configured to perform at least one conversion function, for example, to process three-phase current for an inverter of an electrical machine or to supply distribution current to an electrical load L.

[0039] With reference to the [ Fig.5 [ ] A power module M is represented according to a first embodiment of the invention. The power module M comprises a plurality of power electronic components 2 mounted on a support substrate 1. In this example, the power electronic components 2 are in the form of electronic chips or semiconductors.

[0040] The power module M includes at least one 3P power connector configured to receive power. For example, it is configured to be connected to an electrical load L or a power source S. The 3P power connector is accessible from outside the power module M.

[0041] The M power module includes at least one 3D data connector configured to receive a PCONS control command ([ Fig.4 ]), for example, switching commands for switches or transistors. It is configured, for example, to be connected to a control computer (not shown). The 3D data connector is accessible from outside the M power module.

[0042] In this example, the power electronic components 2 and the connectors 3P, 3D are connected by electrical connections 4, specifically wires ("wire bonding"), but it goes without saying that other types of connection could be suitable. With reference to the [ Fig.5 ], among the electrical connections 4, we distinguish, on the one hand, power electrical connections 4P which allow high currents to flow, for example greater than 10A, and, on the other hand, data electrical connections 4D which allow low currents to flow, for example less than 10A.

[0043] The power module 4 includes an encapsulation layer 5, covering the plurality of power electronic components 2 in order to protect them. Preferably, the encapsulation layer 5 is made of a silicone-based dielectric gel, a thermosetting two-component silicone dielectric gel, or a layer of Parylene insulation. Such an encapsulation layer 5 is known to those skilled in the art. This encapsulation layer 5 advantageously provides electrical insulation. The 3P, 3D connectors have at least a portion extending beyond the encapsulation layer 5.

[0044] The invention is notable in that the power module M comprises at least one fuse protection layer 6 in which extends at least a portion 40 of an electrical connection 4. In this example, several electrical connections 4 comprise a portion 40 in the fuse protection layer 6, in particular, a power electrical connection 4P linking a power electronic component 2 to a power connector 3P, a power electrical connection 4P linking the two power electronic components 2 and a data electrical connection 4D linked to the data connector 3D.

[0045] The fuse protection layer 6 is configured to change state when a current flows above an permissible threshold so as to definitively stop the flow of current in the portions 40 of electrical connection 4 located in the fuse protection layer 6.

[0046] As illustrated in the [ Fig.6 [Schematically representing a power electrical connection 4, a portion 40 is located within the fusible protection layer 6. When a fault occurs inside or outside the power module DP, a current already present in portion 40 of the electrical connection 4 will increase until it exceeds an permissible threshold, preferably at least twice the nominal current flowing through portion 40 of the electrical connection 4 under nominal operating conditions. Within microseconds, portion 40 of the electrical connection 4 will melt, form a liquid bridge, and eventually separate, generating an electric arc.]

[0047] When the permissible threshold is exceeded, the current flowing in portion 40 of the electrical connection 4 causes a change of state in the fusible protection layer 6, which becomes a breaking layer 6', as illustrated in the [ Fig.7 ], which definitively stops traffic in said section 40. Excessive currents can no longer flow, thus protecting the integrity of the power electronic components 2.

[0048] This change of state will allow the energy released by the electrical connection 4 to be absorbed. When the fusible protection layer 6 returns to its original state (solid state), it is transformed into a breaking layer 6' which ensures the definitive interruption of the current flow in the portion 40 of the electrical connection 4.

[0049] The DP power device in which the faulty power module M is used then finds itself in a safe state, due to the cessation of the fault and the ability of the fuse protection layer 6 (breakdown layer 6') to contain the voltage at the electrical connection 4.

[0050] The fusible protective layer 6 is preferably configured to change phase during its state change under the influence of high heat density. Preferably, the fusible protective layer 6 is thermally and chemically stable and compatible with the encapsulation layer 5. Preferably, the fusible protective layer 6 is configured to provide electrical insulation so as to prevent the propagation of electric currents from the power electronic components 2, even when the fusible protective layer 6 becomes a breaking layer 6'. Preferably, the fusible protective layer 6 is hydrophobic and also provides fire resistance without the emission of toxic fumes. Preferably, the fusible protective layer 6 comprises sand, preferably pure silica sand.

[0051] In this example, the fusible protection layer 6 is in direct contact with the encapsulation layer 5.

[0052] With reference to the [ Fig.5 To ensure mechanical protection, the power module is mounted in a housing 7 which preferably includes a base 72 connected to the substrate 1 and a cover 71. Preferably, the 3P, 3D connectors extend beyond the cover 71. In this example, the power module M includes a heat sink 73 to improve heat dissipation, which is connected to the base 72, in particular, via a thermal interface layer. According to one aspect of the invention, the encapsulation layer 15 and the housing 71 are made as a single unit.

[0053] An example of the implementation of a manufacturing process for a power module M will now be presented. The power electronic components 2 are positioned on the substrate 1, preferably of the SnAg type. Preferably, the substrate 1 has been pre-screened to form a redistribution layer for the electrical connectors, and the power electronic components 2 are fixed to the substrate 1 by reflow soldering.

[0054] In this example, the process involves steps consisting of: Connect at least one electrical connection 4 to a power electronic component 2, Deposit an encapsulation layer 5 on the power electronic component 2 so as to protect it, Stabilize the encapsulation layer 5, for example, by an oven curing, polymerization or other operation, and Deposit a fusible protective layer 6 on at least a portion 40 of the power electrical connection 4.

[0055] According to one aspect, the process includes a step of assembling part of the housing 7 before the step of depositing the encapsulation layer 5. This allows the volume of the first part of the housing to be used to facilitate the deposition of the encapsulation layer 5. Preferably, the process includes a step of assembling a second part of the housing 7 after the step of depositing the fusible protection layer 6.

[0056] Preferably, the encapsulation layer 5 is deposited before the fuse protection layer 6 in order to realize the power module M by depositing superimposed layers, which is convenient.

[0057] An example of implementation will be presented with reference to figures 5 à 7 As illustrated in the [ Fig.5 The power module M is powered by the 3P power connector, which supplies power to two power electronic components 2 via 4P power electrical connections. In this example, one power electronic component 2 is also connected to a 3D data connector via a 4D data electrical connection.

[0058] When a short circuit occurs in the power supply system, the current increases rapidly, particularly in 4P power electrical connections as illustrated in the [ Fig.6 ].

[0059] Advantageously, portion 40 of the power electrical connection 4 allows the state of the fuse protection layer 6 to change, transforming it into a breaking layer 6'. In this state, the current flowing in portion 40 of the power electrical connection 4 is permanently stopped, as illustrated in [ Fig.7 This advantageously protects the power electronic components 2 against high currents. Advantageously, the fusible protective layer 6 absorbs the electrical energy to protect the power electronic components 2.

[0060] Preferably, when the fuse protection layer 6 changes state, the current is stopped in all 40 sections, that is, even in those that have not carried a current exceeding the permissible threshold. This is particularly true for the 4D control electrical connection, in which no high current flows.

[0061] The power electronic components 2 are thus protected. An operator only needs to replace the fuse protection layer 6 and the electrical connections 4P, 4D to put the power module M back into service, which is advantageous.

[0062] Another form of realization is represented at the [ Fig.8 For the sake of clarity and conciseness, only the differences with the first form of implementation of the [ Fig.5 The common or analogous elements bear the same references on the [ Fig.8 and will not be described again.

[0063] With reference to the [ Fig.8 The power module M includes a printed circuit board 8, called a "PCB," positioned between the encapsulation layer 5 and the fuse protection layer 6. Advantageously, this allows for easier electrical connections by creating a boundary between the encapsulation layer 5 and the fuse protection layer 6. Furthermore, it provides greater flexibility in choosing materials for the encapsulation layer 5 and the fuse protection layer 6, as they are not in direct contact. This also facilitates the recommissioning process.

[0064] In this example, the power module M includes several remote elements 9, housed in the encapsulation layer 5, which are connected on one side to a power electronic component 2 and on the other side to the printed circuit board 8. The power electrical connection 4 is connected only to the printed circuit board 8 and extends into the fuse protection layer 6, in particular, only into the latter.

[0065] Thus, following the occurrence of an electric arc, the power electrical connections 4 can be conveniently removed along with the fusible protective layer 6. Upon recommissioning, it is simply a matter of recreating the power electrical connections 4 and applying a new fusible protective layer 6. The encapsulation layer 5, the power electronic components 2, and the remote control elements 9 are advantageously unaffected. Preferably, the power electrical connections 4 are pre-wired on the printed circuit board 8, which facilitates assembly and recommissioning.

[0066] Preferably, each offset member 9 is in the form of a vertical pillar mounted on the substrate 1. Preferably, each offset member 9 is connected to a power electronic component 2 via an internal electrical connection 4a which preferably extends only into the encapsulation layer 5 as illustrated in the [ Fig.8 ].

[0067] In this example, with reference to the [ Fig.8 The 3P power connector includes: an internal part 31P, housed in the encapsulation layer 5, which is mounted on one side on the substrate 1 and connected on the other side to the printed circuit board 8, an external part 32P, housed partly in the fuse protection layer 6 and an external link 33P electrically connecting the external part 32P to the internal part 31P via the printed circuit board 8.

[0068] Similarly, the external 33P connection extends only within the fuse protection layer 6. The fuse protection layer 6 is configured to change state when a current exceeding a permissible threshold flows through the external 33P connection, thereby permanently interrupting the current flow. Advantageously, the fuse protection layer 6 can thus change state when an electrical arc occurs in the 3P power connector.

[0069] An example of the implementation of a manufacturing process for a power module M will now be presented. The power electronic components 2 are positioned on the substrate 1. Preferably, the substrate 1 has been pre-screened to form a redistribution layer for the electrical connectors, and the power electronic components 2 are fixed to the substrate 1 by reflow soldering with the offset elements 9 and the internal electrical connections 4a. Preferably, the internal portion 31P of the power connector 3P is also positioned on the substrate 1.

[0070] The process includes a step of depositing an encapsulation layer on the elements positioned on substrate 1 in order to protect them and form a first assembly.

[0071] The process then includes a step of assembling the printed circuit board 8 onto the first assembly. The electrical connections 4, the external link 33P, and the external part 32P of the 3P power connector are preferably pre-wired. Assembly can be carried out by soldering but also, preferably, by a press-fit operation. Compatible offset elements 9 are selected for press-fit assembly. After assembly, the process includes a step of depositing the fusible protective layer 6. This manufacturing process offers considerable flexibility in the choice of material for the encapsulation layer 5 and the fusible protective layer 6, since they are not in direct contact.

[0072] Thanks to the invention, a local current interruption is achieved in a power module M for lower interruption currents than in the prior art. This protects the power electronic components 2 and facilitates restarting. The power of an electric arc is absorbed locally by the fusible protective layer 6. This limits material projection and the spread of damage.

Claims

1. A power module (M) for supplying power to at least one electrical load (L) of an aircraft, the power module (M) comprising a plurality of power electronic components (2) mounted on a support substrate (1), at least one encapsulation layer (5) for encapsulating the plurality of power electronic components (2) in order to protect them, at least one power electrical connection (4) connected to at least one power electronic component (2), the power module (M) comprising at least one fusible protection layer (6), several power electrical connections (4) comprise at least one portion (40) in the fusible protection layer (6), the fusible protection layer (6) being configured to change state when a current, greater than an acceptable threshold, flows in the portion (40) of the power electrical connection (4) so as to permanently stop the flow of current in said portion (40) the fusible protection layer (6) being deposited on the encapsulation layer (5).

2. The power module (M) according to claim 1, wherein the power electrical connection (4) is connected between two power electronic components (2).

3. The power module (M) according to one of claims 1 to 2, wherein the power electrical connection (4) is connected between at least one power electronic component (2) and at least one electrical power connector (3P) comprising at least one portion extending outside the encapsulation layer (5).

4. The power module (M) according to one of claims 1 to 3, comprising at least one offset connector (9) connecting the power electronic component (2) to the power electrical connection (4), the power electrical connection (4) extending only into the fusible protection layer (6).

5. The power module (M) according to claim 4, comprising at least one printed circuit board (8) mounted at the interface between the encapsulation layer and the fusible protection layer (6), the offset connector (9) being connected to the power electrical connection (4) via the printed circuit board (8).

6. The power module (M) according to one of claims 1 to 5, comprising at least one data electrical connection (4D) connected to a data connector (3D), the data electrical connection (4D) comprising at least one portion (40) extending into the fusible protection layer (6).

7. The power module (M) according to one of claims 1 to 6, the power electrical connection (4) of which is in the form of a longitudinal wire comprising several parts (41, 42) with different cross-sections.

8. A power supply system for supplying an aircraft electrical network (REA) comprising at least one power device (DP) comprising at least one power module (M) according to one of claims 1 to 7.

9. A method for manufacturing a power module (M) for supplying power to at least one electrical load (L) of an aircraft, the power module (M) comprising a plurality of power electronic components (2) mounted on a support substrate (1), the method comprising steps consisting in: - Connecting at least one power electrical connection (4) to a power electronic component (2), - Depositing an encapsulation layer (5) on the power electronic component (2) so as to protect it, and - Depositing a fusible protection layer (6) on the encapsulation layer (5) and on at least one portion (40) of the power electrical connection (4), the fusible protection layer (6) being configured to change state when a current, greater than an acceptable threshold, flows in the portion (40) of the power electrical connection (4) so as to permanently stop the flow of current in said portion (40).